From: Martin Schwidefsky <schwidefsky@de.ibm.com>
To: zaitcev@redhat.com
Cc: linux-kernel@vger.kernel.org
Subject: Re: SECURITY - data leakage due to incorrect strncpy implementation
Date: Thu, 29 Jan 2004 09:57:58 +0100 [thread overview]
Message-ID: <20040129085758.GA944@mschwid3.boeblingen.de.ibm.com> (raw)
Hi Pete,
> I do not undestand Alan's position, if he is for it or against it.
> Anyway, in case you want it, here's what I wrote for s390.
> I wrote some userland tests, it seems to check out. BUT I warn you,
> someone better check my assembly.
Learning to write inline assembly? Nice, but it has one small
problem, the count in %r4 is not decremented for 0x00 byte.
Try my little patch.
blue skies,
Martin.
diff -urN linux-2.6.1/arch/s390/lib/strncpy.S linux-2.6.1-s390/arch/s390/lib/strncpy.S
--- linux-2.6.1/arch/s390/lib/strncpy.S Fri Jan 9 07:59:45 2004
+++ linux-2.6.1-s390/arch/s390/lib/strncpy.S Thu Jan 29 09:53:02 2004
@@ -23,8 +23,13 @@
LA 3,1(3)
STC 0,0(1)
LA 1,1(1)
- JZ strncpy_exit # ICM inserted a 0x00
+ JZ strncpy_pad # ICM inserted a 0x00
BRCT 4,strncpy_loop # R4 -= 1, jump to strncpy_loop if > 0
strncpy_exit:
BR 14
-
+strncpy_clear:
+ STC 0,0(1)
+ LA 1,1(1)
+strncpy_pad:
+ BRCT 4,strncpy_clear
+ BR 14
diff -urN linux-2.6.1/arch/s390/lib/strncpy64.S linux-2.6.1-s390/arch/s390/lib/strncpy64.S
--- linux-2.6.1/arch/s390/lib/strncpy64.S Fri Jan 9 07:59:10 2004
+++ linux-2.6.1-s390/arch/s390/lib/strncpy64.S Thu Jan 29 09:53:02 2004
@@ -23,8 +23,13 @@
LA 3,1(3)
STC 0,0(1)
LA 1,1(1)
- JZ strncpy_exit # ICM inserted a 0x00
+ JZ strncpy_pad # ICM inserted a 0x00
BRCTG 4,strncpy_loop # R4 -= 1, jump to strncpy_loop if > 0
strncpy_exit:
BR 14
-
+strncpy_clear:
+ STC 0,0(1)
+ LA 1,1(1)
+strncpy_pad:
+ BRCTG 4,strncpy_clear
+ BR 14
next reply other threads:[~2004-01-29 8:58 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2004-01-29 8:57 Martin Schwidefsky [this message]
-- strict thread matches above, loose matches on Subject: below --
2003-07-11 19:04 Sound updating, security of strlcpy and a question on pci v unload Mikulas Patocka
2003-07-11 21:45 ` SECURITY - data leakage due to incorrect strncpy implementation Alan Cox
2003-07-11 22:10 ` Alan Cox
2003-07-11 23:49 ` Paul Mackerras
2003-07-12 21:28 ` Horst von Brand
2003-07-13 8:02 ` Alan Cox
2003-07-11 22:44 ` Linus Torvalds
2003-07-11 22:50 ` Alan Cox
2004-01-29 3:11 ` Pete Zaitcev
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